What is the process by which a liquid turns into a gas called?

The process by which a liquid turns into a gas is called vaporization. It is a phase transition in which particles in a liquid gain enough energy to enter the vapor or gas state. Vaporization occurs in two main ways: evaporation and boiling.

Evaporation happens at the liquid’s surface and can occur below the boiling point. Faster-moving particles escape first, which is why evaporation can cool the remaining liquid—for example, when sweat evaporates from skin. Boiling occurs throughout the liquid, with vapor bubbles forming when the liquid’s vapor pressure reaches the surrounding pressure. The boiling point therefore changes with altitude and atmospheric pressure.

Vaporization is often confused with sublimation, but sublimation is the direct change from solid to gas without passing through a liquid phase. Melting changes a solid into a liquid, while condensation is the reverse of vaporization: gas changing into liquid. Water vapor is invisible; the white cloud above boiling water is mostly tiny liquid droplets formed as vapor cools.